Accelerator for fire extinguisher system

ABSTRACT

A dry pipe valve accelerator device for a sprinkler system wherein a portion of the accelerator system sensitive to the opening of one or more of the sprinkler valves is isolated from the water supply. In particular, the air pressure in the sprinkler system is continuously monitored by a differential pressure chamber such that a recognition of lowering of air pressure in the piping causes the actuation of a differential pressure responsive valve actuator which in turn permits the rapid opening of the control valve of the sprinkler system.

United States Patent 1,464,614 8/1923 Nacey et a1.

Inventor Philip H. Merdinyan East Greenwich, R.l.

Appl. No. 846,8

Filed Aug. 1, I969 Patented July 27, 1971 Assignee Grinnell CorporationProvidence, R.l.

ACCELERATOR FOR FIRE EXTINGUISHER SYSTEM 13 Claims, 4 Drawing Figs.

U.S.Cl 169/17, 169/20 Int. Cl ..A62c 35/00 Field of Search 169/17, 20.19, 21; 251/62, 63.4, 229

References Cited UNITED STATES PATENTS 1,958,287 5/1934 Tyden 169/172,731,091 1/1956 Robbins 169/17 2,969,842 1/1961 Ault 169/17 PrimaryExaminer- Richard A. Schacher Assistant Examiner-Thomas C. Culp, Jr.Attorney-41. Edward Foerch ABSTRACT: A dry pipe valve accelerator devicefor a sprinkler system wherein a portion of the accelerator systemsensi- -tive to the opening of one or more of the sprinkler valves isisolated from the water supply. In particular, the air pressure in thesprinkler system is continuously monitored by a differential pressurechamber such that a recognition of lowering of air pressure in thepiping causes the actuation of a dif-- ferential pressure responsivevalve actuator which in turn permits the rapid opening of the controlvalve of the sprinkler system.

AccELERA'roRroR rum EXTINCUISHER SYSTEM BACKGROUND OFTIIE INVENTIONpressed air into the ,distribution piping. When undue heat opens one ormore of the automatic sprinklers in a conventional fashion, the airpressure in the piping is altered (reduced), causing a control valve toopen and pass water into the distribution piping from the water supplymain. Generally in order to operate the control valve more rapidly, thatis, where there is only a small pressure drop (i.e. when only onesprinkler valve opens), accelerator devices are included as a part ofthe automatic sprinkler system.

Such accelerator devices have in the past usually comprised an elastomerdiaphragm having a piston position for movement therewith to openthrough a suitable linkage, a valve which in turn opens the-main controlvalve to permit water to flow into the sprinkler distribution pipes. Inaccelerator devices using the diaphragm to sense a change in air presurein the distribution piping, a portion of the water passing through thecontrol valve also passes into the accelerator on one side of thediaphragm (see FIG. 1 prior art). Periodic required testing of suchaccelerators has generally resulted in deterioration of the diaphragmcausing the sameto stick in use, or to lose its sensitivity to detect asmall change in air pressureln addition, since the water is generallydirty, that is carrying a good deal of rust from the pipes, this hasgenerally causedfclo'gging of the orifice for equalizing air pressure onboth sides of the diaphragm thereby effecting the operation of theaccelerator. v

It has been found that the clogging of the orifice has been one of themajor causes'of faulty accelerator operation, and thus there hasdeveloped a great need to overcome thc'excessive maintenance required toinsureproper accelerator operation.

SUMMARY AND OBJECTS OF THE INVENTION means having a medium therein,saidmedium of said control means being isolated from the tireextinguishing medium controlled by said accelerator such that there isno intermingling of the fire extinguishing medium and the controlmedium.

Accordingly, the principal object of the present invention is to provideA a new,- improved, practical and commercially satisfactory acceleratordevice for an automatic fire sprinkler system of the dry pipe character.

Another object of the invention is to provide a new and improvedaccelerator wherein thecontrol means therefore does not come in contactwith the tire extinguishing medium.

A further object of the present invention is to provide a new andimproved accelerator for a dry pipe sprinkler system which avoids thedisadvantages and deficiencies of the prior art diaphragm acceleratorsystems.

Another object of this invention is to provide a new and improvedaccelerator system wherein the pressure sensitive portion of thesystemis isolated from the waterpassing into the distribution piping.

Further objects, advantages and features of the invention will becomeapparent from the following detailed description v of the preferredspecific embodiments illustrated in the drawings.

DESCRIPTIGN OF THE DRAWINGS art diaphragm-type of an accelerator systemfor a dry pipe type of sprinkler system;

FIG. 2 represents a side elevation, shownpartly in vertical section, ofthe preferred form of accelerator device in accordance with theinvention and wherein a portion of the distribution piping is alsoshown; V 7

FIG. 3 represents a diagrammatic illustration of another form accordingto the invention wherein only a portion of the accelerator system isshown, and

FIG. 4 represents a diagrammatic illustration of yet another embodimentaccording to the invention wherein water under pressure rather than airis used as a feedback signal to accelerate the action of the controlvalve.

DESCRIPTION OF THE INVENTION Reference should now be had to FIG. 1 whichdiagrammatically illustrates an accelerator device according to theprior art and which is shown connected to the main valve of thesprinkler system.

The main valve is shown at 10 and includes means for connecting a watermain pipe 11 thereto and means for coupling the sprinklersystemdistribution piping l2 thereto. Within the valve 10 there is shown twoclappers, a larger one at 13 and a smaller one 14, positioned to preventwater from the main pipe 11 from passing therethrough. The largerclapper 13 is held down'by the air pressure in the distribution pipingl2 and maintains the smaller clapper l4 closed. Coupled to the valve 10is an accelerator 20 of the prior art, which includes first and secondchambers 21 and 22 separated by a diaphragm 23 having a diaphragm rod 24supported by parts (not shown) to move therewith. A small orifice 25 isprovided to allow the air pressure on both sides of the diaphragm toequalize. The chamber 21 "is coupled on one side by piping shown at 27to the main valve so that the pressure in the chambers 21 and 22 areboth charged with air at the same pressure of the air (normally 40p.s.i.) in the distribution piping 12. At 28, there is provided pipingfor connecting the chamber 29 (between the two clappers of the mainvalve 10) to the accelerator chamber 21. The piping 28 is normallyclosed by a ball valve arrangement shown at 30. A drip check valve 26drains the chamber 29 so that the air in the chamber 29 is normally atatmospheric pressure.

Upon the opening of one or more of the sprinkler system antomaticsprinklers (not shown), a sudden drop of pressure occurs in chamber 21.Because of the restricted flow through orifice 25, the pressure in thechamber 22 will not follow the sudden drop in pressure in chamber 21.The higher pressure in the chamber 22 causes the diaphragm 23 to movethe rod 24 ina direction to the left in FIG. 1) to upset the ball valve30 so as to permitair under system pressure to flow into the chamber 29with sufficient volume and force to close the drain check. valve and toequalize the air pressure on both sides of clapper 13.

At this point the water pressure of the water in the main 11 causes theclappers l3 and 14 to move upwardlyand open to permit water to flowthrough the valve 10 into the distribution piping 12. As may be seen thewater in the valve will also simultaneously fill up chamber 21 of theaccelerator and cause deterioration of the exposed diaphragm, aspreviously mentioned and in addition cause clogging of the orifice 25.Thus, each time an accelerator is used for testing purposes, theaccelerator must be cleaned out and particularly the orifice must becleaned to insure that it is fully opened.

Reference should now be had to FIG. 2 which shows par tially in section,the preferred embodiment according to this invention coupled to controlor main dry pipe valve shown at 40. At 41 there is shown a water supplymain coupled to the valve 40. The valve 40 is essentially of thedifferential type which is adapted to function on relief of theordinarily maintained pressure in the distribution piping shown at 42.The valve has a clapper or valve 43 held to its seat against anypressure of water in the main 41 by means ofa clapper or valve 44 hingedat 45 and suitably connected to the clapper 43 so that pressure of thefluid (i.e. gas (air) is the chamber 46A will normally keep the waterclapper 43 on its seat. As shown, the clapper 44 has ordinarily a largersurface area exposed to pressure of the air than the pressure area of 44exposed to water, thus insuring the retention of valve 43 on its seatunder the normal conditions of pressures in the pipes 41 and 42. Thedistribution pipe ofthe piping system is connected to the usual pipeshaving outlets thermally controlled, one of such outlets being indicatedat 47 as a usual sprinkler of a typical form wherein an outlet valve isnormally held closed but is adapted to open when released by the actionof heat thereon.

The functioning of the valve 40 in the usual way of the dry pipe systemoccurs when an outlet of the system is opened by the action of heat thusrelieving the air pressure on the clapper 44 and permitting any superiorwater pressure then existing on clapper 43 to open the same and throwback the clapper 44 so that the fire extinguisher medium may pass freelyfrom pipe 41 to 42.

In order to accelerate the opening of the valve 40, there is provided anew and improved accelerator device 49 which includes a chamber 50having a valve arrangement shown at 51. The valve arrangement mayconveniently comprisea ball stem 52 supported in a valve cage 53 whichis pivoted at 54. The valve cage 53 is adapted to normally position theball stem 52 against a valve seat 55 in order to prevent air present inthe chamber 50 from passing through pipe A into the chamber 468 betweenthe two clappers 43 and 44 of the main dry pipe valve. The cage 53 ismaintained in position by a weight 56 shown pivoted at 57, which bearsthereon. Air under pressure is provided to the chamber 50 by way of apipe B coupled to the chamber 46A. Upon rotation of the weight 56 aboutits pivot 57, the member 58 coupled to the weight 56 kicks the ball stem52 and cage 53 off its seat 55 and permits air under pressure to flowthrough pipe A to tend to equalize the air pressure on both sides of theclapper 44, Le. to disturb the balance of the gaseous pressure in themain dry valve, which then permits clapper 43 to open under the pressureof the water against it.

In order to sense the air pressure in the distribution piping 42 thereis provided a branch pipe C coupled to pipe B and which in turn iscoupled to one side of a differential pressure chamber shown at 60,which senses a change in pressure ofthe air in the distribution piping.The chamber includes a piston 61 resiliently biased by a spring 62positioned in a chamber portion 608. On the spring 62 side of the piston61, oil or hydraulic fluid is provided by a pipe network shown generallyat 64 which is filled through plugs 64A. The chamber 60A is coupled viathe pipe network 64 through a restriction 65 to an accumulator shown at70. The accumulator comprises a piston 71 which is adapted to movewithin the accumulator between a lower portion 72A (air at atmosphericpressure) and an upper portion 72B (hydraulic fluid filled). The piston71 is resiliently biased against the hydraulic fluid in the upperportion 728 by a spring 73. Air is permitted to evacuate from the lowerportion 72A via the orifice 74. The accumulator 70 is itself coupledthrough the pipe network 64 to one side of a differential pipe valveactuator shown at 80. The actuator comprises a piston 81 slideablewithin a chamber 82. Hydraulic fluid is provided to the other side ofthe piston 81 via the portion of the piping 64 coupled to thedifferential chamber 60A. Partially positioned within the chamber 82 andslidably movable therein is a rod 83 adapted to be moved to engage theweight 56 in chamber 58 in order to topple the same to open the valvearrangement ln this configuration, the chambers 82 and 50 are separatedby appropriate sealing means (in this case an O-ring about the rod 83)to prevent the passage of fluid (either air or fire extinguishingmedium) from the chamber 50 into the chamber 82 in order to prevent thecomingling of the fluids in both chambers 82 and 50.

The device disclosed above acts as follows: the system (distributionpiping) air pressure is continuously monitored or sensed by thedifferential chamber where it is balanced by the spring 62 and thepressure of the hydraulic fluid therein. Upon the opening ofone of thesprinklers 47, the reduction in the distribution system air pressurecauses piston 61 to fall, thereby reducing the hydraulic fluid pressureon the opposite side of the piston 61 and the pressure of the fluid tothe left of piston 81. Since the fluid on the accumulator side of therestrictor bleeds slowly through the restrictor, the pressure of thehydraulic fluid therein causes the piston 8] to move towards the leftand causes the rod 83 to slidably move and engage the weight 56,toppling the same and causing the ball valve arrangement 51 to open.

The pressure difference on either side of clapper 44 is thereby reducedand clapper 43 opens, as previously described to permit the flow ofwater into the distribution piping 43 from the main 4].

Referring now to FIG. 3, there is diagrammatically shown an alternateembodiment according to this invention. ln this embodiment instead ofapplying the system pressure on both sides of clapper 44, in the eventone or more of the sprinklers 47 open, the air pressure on both sides ofclapper 44 is equalized to atmospheric pressure. This is accomplished byventing pipe A to the atmosphere as shown. The chamber 46B betweenclappers 43 and 44 is vented to atmosphere through the drain check valve89 in a conventional manner and would remain open until water enters thesystem. Thus when one or more of the sprinklers 47 open, the valvearrangement 51 will open as described with regard to the embodiment ofFIG. 5, the air pressure on both sides of clapper 44 will be equalized,and the clappers 43 and 44 will open due to the water pressure in themain 4].

In FIG. 4 there is shown another embodiment in diagrammatic formaccording to this invention. The parts are as previously described withregard to FIGS. 2 and 3 except that in the event that one of the heads47 opens, water under pressure is forced into the chamber 46B betweenthe two clappers to permit both clappers to open. This is accomplishedby coupling pipe A directly to the water main 4] and adding a pipe Dinterconnecting the chamber 468 between two clappers 43 and 44 to thechamber 50. In this embodiment the system air pressure is set so thatthe two clappers will open against the system air pressure in the eventthat water under pressure from the main is forced into the chamber 46Bbetween the two clappers 43 and 44 via pipe A, chamber 50, opened valvevalve 51 and pipe D.

It is apparent from the above description that with this invention thereis prevented a comingling of fire extinguishing fluid and the controlmedia. This not only reduces maintenance as a result of the requiredperiodic testing of such systems but also insures the continuedsensitivity of said accelerator because the orifice or restriction 65 isisolated from the rust and other contaminants in the fire extinguishingmediurn.

This completes the description of the preferred embodiments of thisinvention. It should be understood that various modifications andalterations may be made without departing from the spirit and scope ofthis invention. For example, the valve arrangement 51 may comprise afaucet-type valve; the accumulator may comprise a blatter-typeaccumulator, and the elements of the accelerator may be combined as asingle device with the piping 64 having the shape of fluid passagesformed in a cast housing of the device. It is also to be understood thatthe following claims are intended to cover all of the generic andspecific features of the invention which, as a matter oflanguage, mightbe said to fall therebetween.

What l claim is:

1. An accelerator for use in a dry pipe fire extinguisher system, havingmain valve controlling the admission of a fire extinguishing medium tothe system and normally held closed against the pressure of a supply ofsaid medium by the normal pressure of the gas in the system, sensingmeans including a fluid medium responsive to a change in the pressure ofthe gas in the system, and actuating means responsive to said fluidmedium for disturbing the balance of the gaseous pressure in said mainvalve to permit the same to open, said actuating means comprises firstand second chambers, a control valve in said first chamber; a piston insaid second chamber responsive to said fluid medium, control valveopening means in said first chamber for opening said control valve, andlinkage means positioned between said first and second chambers andresponsive to said piston for acting on said control valve openingmeans.

2. An accelerator according to claim 1 in which said sensing meansincludes a differential pressure chamber responsive to pressure of thegas in the system, fluid passages connecting said differential pressurechamber to said second chamber at point on one side of said piston andalso to an accumulator through an orifice, and a fluid passageconnecting said accumulator to the second chamber at a point on theopposite side of the piston, said fluid medium being present in saidfluid passages, and said accumulator and said differential pressurechambers.

3 An accelerator according to claim 1 in which said linkage meanscomprises a rod movable within both of said first and second chambers.

4, An accelerator according to claim 2 in which said linkage meanscomprises a rod slidably movable within both of said first and secondchambers.

5. An automatic fire extinguisher system including a dry pipe valvecoupling a water main to the distribution piping of a sprinkler system,said dry pipe valve having a first clapper and a second clapper, saidfirst clapper normally maintaining by linkage means said second clapperin a closed position, a dry pipe valve chamber being formed between saidfirst and second clappers, an accelerator responsive to the pressure ofthe air in said distribution piping, said accelerator comprising achamber having an inlet port and an outlet port, said inlet port coupledto the water main, said outlet port coupled to dry pipe valve chamber,and valve means for controlling the flow of fluid from said water mainto said dry pipe valve chamber, said valve means including meansresponsive to a change in the pressure of the air in said distributionpiping.

6. An accelerator for use in a dry pipe fire extinguisher system havinga main valve controlling the admission of a fire extinguishing medium tothe system and normally held closed against the pressure of a supply ofsaid medium by the normal pressure of the gas in the system, actuatingmeans for disturbing the balance of the gaseous pressure in said mainvalve to permit the same to open, control means to control the operationof said actuating means means responsive to a change in pressure in saidsystem to operate said control means, said control means being locatedso that said fire extinguishing medium does not come in contacttherewith.

7. An accelerator device for a dry pipe valve interconnect ing a main todistribution piping comprising a first chamber having an inlet port andan outlet port, valve means in said first chamber for preventing fluidin said first chamber from entering said outlet port, a second chamber,first means positioned in said second chamber and extending into saidfirst to open said valve means of said first chamber, actuating means insaid second chamber to actuate said first means to cause said valvemeans in said first chamber to open, and second means having fluidtherein which is responsive to the pressure of the air in thedistribution piping for actuating said actuating means.

18. A method of controlling a dry pipe valve for coupling a water mainto the distribution piping of a sprinkler system comprising (1) sensingthe pressure of the air in the distribution piping of said sprinklersystem, (2) responsive to a predetermined change of said sensed airpressure, moving a fluid in a separate, closed fluid system includin' aiston to establish a pressure differential on said piston, ant (3 movinga control means outside of said fluid system by movement of said pistonin accordance with said pressure differential to control the opening ofsaid dry pipe valve.

9. An accelerator for use in a dry pipe fire extinguisher system, havingmain valve controlling the admission of a fire extinguishing medium tothe system and normally held closed against the pressure of a supply ofsaid medium by the normal pressure of the gas in the system, sensingmeans including a fluid medium responsive to a change in the pressure ofthe gas in the system, said sensing means including separating meanspositioned between said fluid medium of said sensing means and said fireextinguishing system for closing said sensing means to intermingling ofsaid fire extinguishing medium with the medium of said sensing means,and actuating means responsive to said fluid medium for disturbing thebalance of the gaseous pressure in said main valve to permit the same toopen.

10. An accelerator for a dry pipe fire extinguisher system having a mainvalve controlling the flow ofa fire extinguishing fluid into the systemand held closed by a gas pressure in said system, comprising controlmeans for disturbing the balance of pressures on said main valve tocause said main valve to open, a closed fluid conduit means including afluid moving means having a movable surface face for sensing thepressure of said gas in said fire extinguisher system and for movingfluid in said fluid conduit system in accordance with said sensed gaspressure, piston means operatively connected to said control means, saidfluid conduit means further including means for establishing a fluidpressure differential on opposed surfaces of said piston meansresponsive to change in said air pressure, whereby said pressuredifferential moves said piston to actuate said control device when saidair pressure decreases at a rate which is greater than a predeterminedrate.

11. An accelerator according to claim 10, in which said sensing meanscomprises a cylinder and piston, one surface of said pistoncommunicating with said gas pressure in said fire extinguisher systemand an opposing surface of said piston communicating with fluid in saidclosed fluid system.

12. An accelerator according to claim 11, in which said sensing pistonis resiliently biased toward said gas pressure.

13. An accelerator according to claim 10, in which said means forestablishing a pressure differential on said piston means includes anaccumulator and an orifice located in said closed fluid system betweensaid sensing means and said accumulator and between said opposedsurfaces of said piston means.

1. An accelerator for use in a dry pipe fire extinguisher system, havingmain valve controlling the admission of a fire extinguishing medium tothe system and normally held closed against the pressure of a supply ofsaid medium by the normal pressure of the gas in the system, sensingmeans including a fluid medium responsive to a change in the pressure ofthe gas in the system, and actuating means responsive to said fluidmedium for disturbing the balance of the gaseous pressure in said mainvalve to permit the same to open, said actuating means comprises firstand second chambers, a control valve in said first chamber; a piston insaid second chamber responsive to said fluid medium, control valveopening means in said first chamber for opening said control valve, andlinkage means positioned between said first and second chambers andresponsive to said piston for acting on said control valve openingmeans.
 2. An accelerator according to claim 1 in which said sensingmeans includes a differential pressure chamber responsive to pressure ofthe gas in the system, fluid passages connecting said differentialpressure chamber to said second chamber at point on one side of saidpiston and also to an accumulator through an orifice, and a fluidpassage connecting said accumulator to the second chamber at a point onthe opposite side of the piston, said fluid medium being present in saidfluid passages, and said accumulator and said differential pressurechambers. 3 An accelerator according to claim 1 in which said linkagemeans comprises a rod movable within both of said first and secondchambers. 4, An accelerator according to claim 2 in which said linkagemeans comprises a rod slidably movable within both of said first andsecond chambers.
 5. An automatic fire extinguisher system including adry pipe valve coupling a water main to the distribution piping of asprinkler system, said dry pipe valve having a first clapper and asecond clapper, said first clapper normally maintaining by linkage meanssaid second clapper in a closed position, a dry pipe valve chamber beingformed between said first and second clappers, an accelerator responsiveto the pressure of the air in said distribution piping, said acceleratorcomprising a chamber having an inlet port and an outlet port, said inletport coupled to the water main, said outlet port coupled to dry pipevalve chamber, and valve means for controlling the flow of fluid fromsaid water main to said dry pipe valve chamber, said valve meansincluding means responsive to a change in the pressure of the air insaid distribution piping.
 6. An accelerator for use in a dry pipe fireextinguisher system having a main valve controlling the admission of afire extinguishing medium to the system and normally held closed againstthe pressure of a supply of said medium by the normal pressure of thegas in the system, actuating means for disturbing the balance of thegaseous pressure in said main valve to permit the same to open, controlmeans to control the operation of said actuating means, means responsiveto a change in pressure in said system to operate said control means,said control means being located so that said fire extinguishing mediumdoes not come in contact therewith.
 7. An accelerator device for a drypipe valve interconnecting a main to distribution piping comprising afirst chamber having an inlet port and an outlet port, valve means insaid first chamber for preventing fluid in said first chamber fromentering said outlet port, a second chamber, first means positioned insaid second chamber and extending into said first to open said valvemeans of said first chamber, actuating means in said second chamber toactuate said first means to cause said valve means in said first chamberto open, and second means having fluid therein which is responsive tothe pressure of the air in the distribution piping for actuating saidactuating means.
 9. An accelerator for use in a dry pipe fireextinguisher system, having main valve controlling the admission of afire extinguishing medium to the system and normally held closed againstthe pressure of a supply of said medium by the normal pressure of thegas in the system, sensing means including a fluid medium responsive toa change in the pressure of the gas in the system, said sensing meansincluding separating means positioned between said fluid medium of saidsensing means and said fire extinguishing system for closing saidsensing means to intermingling of said fire extinguishing medium withthe medium of said sensing means, and actuating means responsive to saidfluid medium for disturbing the balance of the gaseous pressure in saidmain valve to permit the same to open.
 10. An accelerator for a dry pipefire extinguisher system having a main valve controlling the flow of afire extinguishing fluid into the system and held closed by a gaspressure in said system, comprising control means for disturbing thebalance of pressures on said main valve to cause said main valve toopen, a closed fluid conduit means including a fluid moving means havinga movable surface face for sensing the pressure of said gas in said fireextinguisher system and for moving fluid in said fluid conduit system inaccordance with said sensed gas pressure, piston means operativelyconnected to said control means, said fluid conduit means furtherincluding means for establishing a fluid pressure differential onopposed surfaces of said piston means responsive to change in said airpressure, whereby said pressure differential moves said piston toactuate said control device when said air pressure decreases at a ratewhich is greater than a predetermined rate.
 11. An accelerator accordingto claim 10, in which said sensing means comprises a cylinder andpiston, one surface of said piston communicating with said gas pressurein said fire extinguisher system and an opposing surface of said pistoncommunicating with fluid in said closed fluid system.
 12. An acceleratoraccording to claim 11, in which said sensing piston is resilientlybiased toward said gas pressure.
 13. An accelerator according to claim10, in which said means for establishing a pressure differential on saidpiston means includes an accumulator and an orifice located in saidclosed fluid system between said sensing means and said accumulator andbetween said opposed surfaces of said piston means.
 18. A method ofcontrolling a dry pipe valve for coupling a water main to thedistribution piping of a sprinkler system comprising (1) sensing thepressure of the air in the distribution piping of said sprinkler system,(2) responsive to a predetermined change of said sensed air pressure,moving a fluid in a separate, closed fluid system including a piston toestablish a pressure differential on said piston, and (3) moving acontrol means outside of said fluid system by movement of said piston inaccordance with said pressure differential to control the opening ofsaid dry pipe valve.